Method for producing polymer of ethylene

Abstract

A process for preparing a polymer of ethylene having a flow activation energy higher than that of a substantially linear ethylene polymer of the same molecular weight involving using bridged sandwich-bonded fluorenyl-containing metallocenes and the polymers resulting therefrom.

That which is claimed: 
     
       1. A process for preparing a polymer of ethylene having a flow activation energy of at least about 25 kJ/mol, comprising contacting ethylene in a liquid diluent with a catalyst system comprising: (1) a catalyst comprising 1-(9-fluorenyl)-2-(indenyl) ethane zirconium dichloride, and   (2) a cocatalyst for said metallocene.   
     
     
       2. A process according to claim 1 wherein said cocatalyst comprises an aluminoxy co-catalyst having repeating units of the formula ##STR4## wherein, R is a hydrocarbyl group. 
     
     
       3. A process according to claim 2 which produces a polymer of ethylene having a density of less than 0.92 g/cc and a flow activation energy of at least 35 kJ/mol. 
     
     
       4. A process according to claim 1 wherein said polymerization is conducted at a temperature in the range of about 60° C. to about 111° C. in a liquid diluent consisting essentially of isobutane. 
     
     
       5. A process according to claim 4 wherein ethylene is polymerized in the absence of comonomer to produce a polymer having a flow activation energy of at least about 30, weight average molecular weight of at least 30,000, an HI in the range of 2 to 20, and a density of at least about 0.94 cc/g. 
     
     
       6. A process according to claim 4 wherein ethylene is polymerized in the presence of an acyclic comonomer having 4 to 12 carbon atoms. 
     
     
       7. A process according to claim 4 wherein ethylene is copolymerized with hexene-1. 
     
     
       8. A process according to claim 7 wherein said cocatalyst is a solid hydrocarbyl aluminoxy cocatalyst prepared by reacting methylaluminoxane and an organoboroxine. 
     
     
       9. A process for preparing a polymer of ethylene having a flow activation energy of at least about 25 kJ/mol comprising contacting ethylene in the presence of an acyclic olefinic comonomer having 4 to 12 carbon atoms in a liquid diluent wherein the molar ratio of the comonomer employed to the ethylene employed is in the range of from about 0.025/1 to about 0.5/1 and the resulting copolymer has a density in the range of 0.88 to about 0.96 g/cc using a catalyst system comprising: (1) a fluorenyl-containing metallocene selected from compounds of the formula (Z)--R'--(Z')MeQ 2  wherein R' is selected from --CH 2  CH 2  --, --CH 2  --, and dimethylsilylene, and each Q is a halide, Z is a substituted or unsubstituted fluorenyl radical, Z' is a substituted or unsubstituted fluorenyl radical, a substituted or unsubstituted indenyl radical, a substituted or unsubstituted cyclopentadienyl radical, a tetrahydroindenyl radical, or an octahydrofluorenyl radical; Me is selected from Zr and Hf, and   (2) a cocatalyst for said metallocene.   
     
     
       10. A process according to claim 9 wherein said cocatlyst comprises an aluminoxy co-catalyst having repeating units of the formula ##STR5## wherein R is a hydrocarbyl group. 
     
     
       11. A process according to claim 9 wherein Me is Zr. 
     
     
       12. A process according to claim 11 wherein R' is dimethylsilylene. 
     
     
       13. A process according to claim 9 wherein said catalyst comprises 1-(9-fluorenyl)-1-(cyclopentadienyl) methane zirconium dichloride. 
     
     
       14. A process according to claim 9 wherein said catalyst comprises 1-(9-fluorenyl)-2-(indenyl) ethane zirconium dichloride. 
     
     
       15. A process according to claim 9 wherein said catalyst comprises 1-(9-fluorenyl)-1-(indenyl) dimethyl silane zirconium dichloride. 
     
     
       16. A process according to claim 9 wherein said catalyst comprises bis 1,2-(9-fluorenyl) ethane zirconium dichloride. 
     
     
       17. A process according to claim 9 wherein said catalyst comprises 1-(9-fluorenyl)-1-(3-prop-1-enyl indenyl) dimethyl silane zirconium dichloride. 
     
     
       18. A process according to claim 9 wherein Z' is selected from substituted or unsubstituted indenyl. 
     
     
       19. A process according to claim 11 wherein Z' is selected from substituted or unsubstituted indenyl. 
     
     
       20. A process according to claim 9 wherein the molar ratio of comonomer employed to ethylene employed is in the range of from about 0.025/1 to about 0.5/1 and the resulting copolymer has a molecular weight of at least about 30,000 and a density in the range of from about 0.88 to about 0.96 g/cc. 
     
     
       21. A process according to claim 9 wherein ethylene is copolymerized with hexene-1. 
     
     
       22. A process according to claim 21 wherein said copolymerization is conducted at a temperature in the range of about 60° C. to about 111° C. and the liquid diluent consists essentially of isobutane. 
     
     
       23. A process according to claim 22 which produces a polymer of ethylene having a flow activation energy in the range of about 30 to about 60 kJ/mol and a density of less than 0.92 g/cc. 
     
     
       24. A process according to claim 23 which produces a polymer of ethylene having an HI of 6 or less. 
     
     
       25. A process according to claim 23 which produces a polymer of ethylene having an HI greater than 6 and less than 20.